BOSTON — The state’s top gambling regulator told representatives from the cities of Boston and Everett on Wednesday that they needed to resolve by week’s end a dispute over how much say, if any, Boston should have on a resort casino proposed by Las Vegas casino developer Steve Wynn.

Attorneys representing Wynn and Boston Mayor Thomas Menino offered the Massachusetts Gaming Commission conflicting opinions as to whether any portion of the $1.2 billion project — planned at the site of a former Monsanto chemical plant along the Mystic River — would lie within the borders of Boston’s Charlestown neighborhood.

At issue is whether Boston should be considered, for the purposes of the Wynn casino, a host community or a surrounding community. The distinction is a critical one: If Boston is deemed a host community, Wynn would be forced to negotiate an agreement with Menino that would be voted on by Charlestown residents. Reaching such an agreement is considered unlikely given Menino’s strong support for a competing casino plan at Suffolk Downs.

If Boston’s status is that of a surrounding community, the city could negotiate compensation for any impact the casino might cause but would have no direct say on whether the development goes forward.

Former Massachusetts Gov. William Weld, now a private attorney and representing Wynn, told the panel that records on file in the Middlesex County land court proved that all the property involved in the proposed development was located in Everett.

“The parcel does not contain any land or structure in Boston or Suffolk County,” said Weld, adding that he believed Boston should be designated as a surrounding community.

But Boston officials, in their presentation to the commission, based their contentions on a geographical oddity: A sliver of land just north of the river, surrounded on both sides by Everett, actually belongs to the city of Boston, they said.

Lawrence Kaplan, an attorney working for the city, said Boston officials had tried repeatedly to learn more about the site plan, but Wynn’s representatives had not cooperated.

“There have been several inconsistent images that have been presented by the Wynn representatives, several of them that show the project is in the city of Boston,” Kaplan said. “These are their own images, not images that we have produced.”

Wynn’s representatives said while the developer had signed an option to purchase the disputed slice of land, there were no plans to build on it anything associated with the gambling establishment.

The Boston delegation stopped short of declaring the city should be a host community, instead asking the commission to clear up the confusion. Stephen Crosby, the panel’s chairman, ordered both sides to meet and try to settle the matter by Friday, after which the commission would step in if there was no resolution.

The dispute has created tensions between officials in Boston and in the much smaller city of Everett, who have accused Menino of bullying tactics.

But Weld said there was nothing personal.

“We love Tom Menino. We love the city of Boston,” he said. “We want the city … to receive fair compensation for any and all impacts, particularly on the Charlestown area.”